Drop hammer



F. E. SMITH DROP HAMMER Oct. 8, 1968 4 Sheets-Sheet 1 Filed Aug. 9, 1966I N vENToR FORREST E. SMITH 4 WJ L ,MM /JQ QM A'rws,

Oct. 8, 1968 F. E. SMITH 3,404,847.

DROP HAMMER Filed Aug. 9, 1966 4 Sheets-Sheet 2 .I EN'TOR FORREST .SMITHbyjw$% Hum E. SMITH DROP HAMMER 4 sheet -s 5 Filed Aug. 9, 1966 MM TiINVENTO FORREST E. SMITH BY A/ %,%J ATTYS.

United States Patent 3,404,847 DROP HAMMER Forrest E. Smith, 151 Point"Circle Jupiter Tequesta, Fla. 33458 Filed Aug. 9, 1966, Ser. No. 571,23514 Claims. (Cl. 241291) The present invention relates generally to animproved massive body or weight of the type utilized for breaking rocksor other materials and which may also be utilized in various other typesof demolition operations. In its principal aspect the invention isconcerned with improved heavy bodies of the foregoing type characterizedby greater toughness, hardness, strength and durability to withstandextreme impact and abrasion in use and yet may also include provision tocompensate for weight loss that occurs over the useful life thereof.

It has been common practice in quarrying operations or the like toutilize a very heavy inertia body to break large rocks or othermaterials into smaller pieces thereby rendering the material moresuitable for subsequent handling. When rock is dynamited loose in aquarry, frequently the size of the rock obtained is still too large tobe crushed by rotary or other available types of mechanical crushers.Heavy bodies, commonly referred to as drop hammers, are utilized tofurther break the rock to a more useful size by lifting the hammer to arequired height with a crane and allowing the hammer to freely drop onthe oversized rock to be broken.

In order to break large rock pieces into acceptable sizes, the hammermust be quite heavy, especially when Working with granite or other hardrock. However, the weight of the hammer should not be too excessive forthe equipment which is to handle the hammer. The hammer must be of asize which is capable of being hoisted by a crane several hundred timesa day and yet of a size permitting eflicient breaking of the rocks. Inactual practice, it has been customary to start with a hammer having aweight closely approaching the maximum continuous operating capabilityof the hoisting equipment, eg when using a crane rated at approximately1%. yard size with a boom length of 50 to 60 feet, the hammer weighsapproximately 10,000 pounds, and the hammer is discarded when it is worndown by repeated impacts with rock at the point when it is no longerheavy enough to be effective when dropped from a practical height. Withthe exemplary 10,000 pound hammer, it is customary to discard the hammerwhen the weight is reduced to around 5,000 or 6,000 pounds.

In view of the obvious economic loss incurred by having to discard worndown hammers, often at a very low salvage value, numerous differentapproaches have heretofore been utilized to avoid having to throw awaysuch a large portion of the original drop body. For example, oneapproach has involved the use of a discardable or replaceable shoe typeattachable member. This type of construction is multi-part and includesa relatively heavy drop body and a replaceable shoe type wearing portionwhich is attached to the drop body by a relatively thin stem. While theshoe portion can be relatively easy to replace, both the shoe and theconnecting stem are easily deformed and broken in normal operation andin many cases, this occurs even after only a few hours usage.Consequently, such drop hammers require continual shoe replacement andtherefore do not solve the problem of economic loss sustained throughwear of the hammer.

Other approaches have been to seek metals or methods of treating themetals to possess a much required resistance to impact wear and abrasionto which such hammers are subjected. Certain metals such as austeniticmanganese (Hadfield) steels which do possess the necessary qualities oftoughness, hardness, strength and durability have been completelyoverlooked or intentionally discarded by the industry. Even though ithas been found to be particularly useful in mining equipment for orecrushing, digger teeth and the like, the industry has here toforeconsidered this material not satisfactory for use in drop hammers andcertain limitations to the use of this steel have been set. Due to thehigh coefficient of thermal expansion (about 1 /2 times that of pureiron) and the low heat conductivity (about that of carbon steel) thereis a great difference in the cooling rates of the exterior and interiorof a manganese steel piece when subjected to the drastic heat treatmentrequired to form articles of this material. To dissolve the carbide inthe austenite, manganese steel must be heated to over 1800 F. andquenched in cold water, however, the lag of the inside of the metal incooling coupled with the high coefficient of expansion, sets up stressesof such magnitude that large sections of manganese steel of thicknessesgreater than the effective penetration depth of the coolant cannot bequenched without producing cracks which generally start within the bodyand work toward the surface.

Accordingly, it is a general aim of the present invention to p ovide animproved drop hammer which overcomes all of the foregoing disadvantagesand which is characterized by its ability to permit substantially longerperiods of usage than heretofore possible, yet wherein this result isachieved without effecting the operating efficiency or causingsubstantial economic loss.

A related object of the invention is the provision of an improved drophammer adapted to maintain a relatively constant weight for maintainingthe most effective operating efiiciency when used in material breakingoperations. In this connection it is an object of the present inventionto provide an improved drop hammer wherein when weight loss occursthrough wear, such loss can be readily compensated by adding a low costmaterial directly to the body portion in order to retain the mostelfective operating efiiciency.

In another of its important aspects, it is an object of the invention toprovide an improved drop hammer which can be constructed of a tough, lowwearing coeflicient alloy steel capable of withstanding the impact andabrasion to which such drop hammers are subjected to a much greaterextent and for a longer period of time than heretofore possible. Thus,it is an object of the present invention to provide a drop hammer whichmay be made of austenitic manganese steel or the like.

It is yet another object related to the foregoing to provide a drophammer cast from manganese steel or the like wherein provision is madeto facilitate proper heat treatment of all portions of the metal, yetpermitting a drop body of suitable weight and mass to be formed enablingthe hammer to be used to break oversized rocks and the like.

It is finally an object to provide a drop hammer formed of castmanganese steel that may be effectively heat treated yet avoids internalstrains and fissures or cracks which would cause a weakening of suchstructures.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIGURE 1 is an exemplary illustration showing a drop hammer craneincorporting the features of the present invention;

FIG. 2 is an enlarged elevation view, partly in section of the drophammer shown in FIG. 1;

FIG. 3 is a fragmentary, enlarged front side view of the 'drop hammer inFIG. .2;

FIG. 4 is a top view of the drop hammer in FIG. 3;

FIG. 5 is an elevation view, partly in section, similar to FIG. 2 buthere depicting a slightly modified form of '13 drop hammer alsoembodying the features of the present invention;

FIG. 6 is a transverse section taken substantially along the line 6-6 inFIG.

FIG. 7 is a fragmentary, front side view of the drop hammer in FIG. 5;and

FIG. 8 is an elevation view partly in section of still another slightlymodified form of the present invention.

While the invention is susceptible of various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Itshould be understood, however, that it is not intended to limit theinvention to the particular forms disclosed, but, on the contrary, theintention is to cover all modifications, equivalents and alternativesfalling within the spirit and scope of the invention as expressed in theappended claims.

Referring now to the drawings, and particularly to FIGS. 1 and 2, thereis illustrated an exemplary drop hammer, generally indicated at 10,which is particularly suited for being lifted to a required height by atraveling crane 12 and allowed to freely drop on a rock 14 or the likein order to break the rock into smaller pieces more suitable forsubsequent handling. As best shown in FIG. 2, the exemplary drop hammerincludes a heavy drop body 16 which is generally cylindrical in shape.It will be understood, however, that the body 16 may be of any suitablesize or shape depending upon the use to which it is put and may, forexample, be spherical in its general outer configuration while circularor polygonal in cross-section.

For the purpose of connecting the drop hammer to the cable 18 of crane12, there is provided a suitable hitch member 20 formed at the upper end21 of body 16. The hitch member 20 includes aligned openings 22 throughwebs 23 projecting from the body 16. The cable 18 may be attached tomember 22 by any connection loop or hitching means.

In accordance with one of the important aspects of the presentinvention, the drop body 16 is constructed of manganese steel whereinprovision is made to insure that proper heat treatment of all portionsof the metal can be effected. Thus, a drop body in accordance with thepresent invention can be formed of any suitable weight and mass and iscapable of withstanding the impact and abrasion to which such drophammers are subjected to a much greater extent and for a longer periodof time. To this end, referring to the exemplary drop hammerconstruction shown in FIG. 2, the body 16 is formed of a plurality ofsections or walls 24 with the walls having a maximum allowable thicknessT not exceeding the effective penetrating depth of a quenching liquid orcoolant when heat treating the walls.

In the case of manganese steel, heat treatment is effected by heatingabove 1800 F. and then plunging into a coolant such as cold water or thelike which gels the grain structure of the metal and results in a steelwholly austenitic in nature and extremely durable and strong. In orderto properly heat treat manganese steel avoiding internal strains andfissures or cracks, no portion of the metal between cooling surfacesshould be greater than approximately 2 inches from a cooling surface,and the thickness of heat treatable sections is preferably not overapproximately 4 inches thick.

In the exemplary form of drop hammer shown in FIG. 2, the body is castfrom manganese steel and to facilitate rapid cooling of the body afterheat treatment, thereby tempering and toughening the metal, a pluralityof passages 28 are provided for circulation of a quenching fluid throughthe body thus positively rendering every portion of the body Walls 24tough and homogeneous. In this form of the present invention, FIG. 4,the body walls 24 are in the form of a plurality of concentric spacedtubular sections with a plurality of radially extending spokes ormembers 32 interconnecting tubular sections to define the passages 28 inthe body. Both the tubular sections 24 and the members 32 are uniform insection and their respective thicknesses do not exceed the maximumpenetration depth of the quenching liquid circulated through thepassages 28 and about the outer surface of the body. In keeping withthis form of the invention shown in FIG. 4, the passages 28 aredimensioned so as to permit sufficient flow of quenching liquidtherethrough. While the maximum thickness of the tubular sections 24 andinterconnecting members 32 for effecting adequate heat treatment of themetal is approximately 5 inches, it is preferred that the members hemade within the range of approximately 3 to 4 inches so that there is noportion of metal that would be beyond the penetrating reach of coolantflowing about the surface of the body and through the passages when itis quenched.

Upon plunging the heated body into a volume of liquid coolant, it willbe noted that liquid will flow upward through the passages 28 due topressure of displacement by the massive body and the outside surface ofthe body will be surrounded by coolant so that proper heat treatmentwill be obtained for every portion of metal forming the body.

It will be appreciated by those skilled in the art, tha while only threetubular sections 24 interconnected'by members 32 are shown, that thisnumber as well as the length of the body may be varied within relativelywide limits depending upon the total weight of the drop hammer that isdesired.

Referring now to FIGS. 5, 6, and 7, a slightly modified form of drophammer, generally indicated at 40, has been depicted. In this instance,and in accordance with another important aspect of the presentinvention, provision is made on the one hand to increase the weight ofthe body or on the other hand, to compensate for weight loss upon usethereby enabling the body portion to be used for greater lengths of timewithout any appreciable loss of operating efiiciency. To this end, acavity 42 is provide in the upper end portion 21a of the body portion 40while the lower end portion 43 is substantially the same constructionshown in the previous embodiment. In this instance, molten lead or anyother suitable mass of relatively heavy material can be poured into thecavity 42 through openings 44 between web members 46 at the top of thebody. Cylindrical member 47 supported by webs 46 serves as means toattach the cable to the drop hammer.

One of the advantages of the present form of the invention is that theprovision of the cavity 42 for receiving a relatively heavy mass ofmaterial enables the use of a standardized, basic drop hammer whereinthe weight can be increased very simply and economically should the userdesire a heavier drop hammer for more rugged ap plications. A furtheradvantage of the invention is that as the lower portion 43 of the drophammer is worn away additional mass of relatively heavy material can beadded in cavity 42 maintaining the operating efliciency without havingto thrown away a large portion of the original body as was necessarywith previous types of drop hammers.

For the purpose of preventing molten lead or other relatively heavymaterial added in cavity 42 from flowing downwardly through the passages28a plugs 48 are provided which may be formed of metal, refractorymaterials or other composite materials having a melting or flash pointhigher than that of the molten lead or other material being poured intothe cavity. Other manners of covering the passage openings mayalternatively be utilized without departing from the present invention.

In keeping with the foregoing important aspect of the present invention,referring to FIG. 8, there is shown still a further modified form of thepresent invention wherein the drop hammer body portion 40a stillincludes the cavity 42a for receiving a relatively heavy mass ofmaterial, however, in this instance the lower portion 43a of the drophammer is constructed of any suitable tough, low wearing coeflicientsteel or alloy capable of withstanding the impact and abrasion in use.Since the drop hammer includes the cavity 42a, lead or other heavymaterial may be added to compensate for weight loss due to wearing ofthe lower portion, thus extending the life of the hammer considerably.In either case, that is, whether at least the lower portion is formed ofaustenitic manganese steels or other suitable wea-r resistent anddurable metals, the inclusion of the fillable cavity enables the user toextend the life of the drop hammer without sacrificing efficiency or toeasily change the weight of a single drop hammer for use with differingcrane and boom capacities without maintaining a stock of diiferent sizeddrop hammers.

I claim as my invention:

1. A drop hammer comprising a heavy drop body of heat treatable materialhaving upper and lower end portions, at least the lower end portionhaving a plurality of sections therein defining walls in said body, saidwalls having a maximum thickness not exceeding the efiective penetratingdepth of a quenching liquid for effecting heat treatment of saidsections.

2. A drop hammer as claimed in claim 1 wherein the upper end portion ofsaid body includes a cavity adapted to receive a mass of relativelyheavy material to increase the weight of said drop hammer.

3. A drop hammer as claimed in claim 1 wherein said heat treatablematerial is austenitic manganese steel.

4. A drop hammer as claimed in claim 3 wherein said maximum wallthickness is five inches.

5. A drop hammer as claimed in claim 3 wherein the walls aresubstantally uniform in section and said wall thickness is approximately3 /2 to 4 /2 inches.

6. A drop hammer as claimed in claim 2 wherein said mass of relativelyheavy material is lead.

7. A drop hammer comprising a heavy drop body of cast heat treatablematerial, said body including a plurality of concentric spaced tubularsections, a plurality of radially extending members interconnecting saidtubular sections to define a plurality of passages in said body forcirculation of a quenching liquid therethrough to effect heat treatmentof the body and the tubular sections and radially extending membershaving a maximum thickness not exceeding the elfective penetrating depthof quenching liquid circulating between respective adjacent ones of saidpassages and between respective ones of said passages and the outersurface of the body.

8. A drop hammer as claimed in claim 7 wherein said heat treatablematerial is austenitic manganese steel and said sections and members areuniform in cross section.

9. A drop hammer as claimed in claim 8 wherein said tubular sections andradial members are approximately 3 to 4 /2 inches thick.

10. A drop hammer comprising a heavy drop body of heat treatablematerial having upper and lower end portions, at least the lower endportion having a plurality of passages therein defining interconnectingwalls in said body, and the walls between said passages and the outersurface of said body having a maximum thickness not exceeding theeffective penetrating depth of a quenching liquid for heat treating saidwalls when circulated through said passages and about the outer surfaceof said body.

11. A drop hammer as claimed in claim 10 wherein said heat treatablematerial is austenitic manganese steel.

12. A drop hammer as claimed in claim 10 wherein the upper end portionof said body includes a cavity adapted to receive amass of relativelyheavy material to increase the weight of said drop hammer.

13. A drop hammer as claimed in claim 11 wherein the walls aresubstantially uniform in section and said wall thickness isapproximately 3 /2 to 4 /2 inches.

14. A drop hammer comprising a heavy drop body including upper and lowerend portions, the upper end portion of said body including a cavityadapted to receive a mass of relatively heavy material and meansdefining an opening at the upper end of said body for adding said massto compensate for a loss weight due to wearing away of the lower endportion during use.

References Cited UNITED STATES PATENTS 2,524,589 10/1950 Becker 241-29lX 2,660,110 11/1953 Boutwell 241-291 {HARRISON L. HINSON, PrimaryExaminer.

1. A DROP HAMMER COMPRISING A HEAVY DROP BODY OF HEAT TREATABLE MATERIALHAVING UPPER AND LOWER END PORTIONS, AT LEAST THE LOWER END PORTIONHAVING A PLURALITY OF SECTIONS THEREIN DEFINING WALLS IN SAID BODY, SAIDWALLS HAVING A MAXIMUM THICKNESS NOT EXCEEDING THE EFFECTIVE PENETRATINGDEPTH OF A QUENCHING LIQUID FOR EFFECTING HEAT TREATMENT OF SAIDSECTIONS.